**String Theory and the Scientific Method**

By Richard Dawid

Cambridge University Press (2013)

“String Theory and the Scientific Method” is a very interesting and timely book by a philosopher trying to make sense out of trends in contemporary theoretical physics. Dawid has collected arguments that physicists have raised to demonstrate the promise of their theories, arguments that however are not supported by the scientific method as it is currently understood. He focuses on string theory, but some of his observations are more general than this.

There is for example that physicists rely on mathematical consistency as a guide, even though this is clearly not an experimental assessment. A theory that isn’t mathematically consistent in some regime where we do not have observations yet isn’t considered fundamentally valid. I have to admit it wouldn’t even have occurred to me to call this a “non-empirical assessment,” because our use of mathematics is clearly based on the observation that it works very well to describe nature.

The three arguments that Dawid has collected which are commonly raised by string theorists to support their belief that string theory is a promising theory of everything are:

**Meta-inductive inference**: The trust in a theory is higher if its development is based on extending existing successful research programs.**No-alternatives argument**: The more time passes in which we fail to find a theory as successful as string theory in combining quantum field theory with general relativity the more likely it is that the one theory we have found is unique and correct.- Argument of
**unexpected explanatory coherence**: A finding is perceived more important if it wasn’t expected.

In the introduction Dawid writes explicitly that he only studies the philosophical aspects of the development and not the sociological ones. My main problem with the book is that I don’t think one can separate these two aspects clearly. Look at the arguments that he raises: The No Alternatives Argument and the Unexpected Explanatory Coherence are explicitly sociological. They are 1.) based on the observation that there exists a large research area which attracts much funding and many young people and 2.) that physicists trust their colleagues’ conclusions better if it wasn’t the conclusion they were looking for. How can you analyze the relevance of these arguments without taking into account sociological (and economic) considerations?

The other problem with Dawid’s argument is that he confuses the Scientific Method with the rest of the scientific process that happens in the communities. Science basically operates as a self-organized adaptive system, that is in the same class of systems as natural selection. For such systems to be able to self-optimize something – in the case of science the use of theories for the descriptions of nature – they must have a mechanism of variation and a mechanism for assessment of the variation followed by a feedback. In the case of natural selection the variation is genetic mixing and mutation, the assessment is whether the result survives, the feedback is another reproduction. In science the variation is a new theory and the assessment is whether it agrees with experimental test. The feedback is the revision or trashcanning of the theory. This assessment whether a theory describes observation is the defining part of science – you can’t change this assessment without changing what science does because it determines what we optimize for.

The assessments that Dawid, correctly, observes are a pre-selection that is meant to assure we spend time only on those theories (gene combinations) that are promising. To make a crude analogy, we clearly do some pre-selection in our choice of partners that determines which genetic combinations are ever put to test. These might be good choices or they might be bad choices and as long as their success hasn’t also been put to test, we have to be very careful whether we rely on them. It’s the same with the assessments that Dawid observes. Absent experimental test, we don’t know if using these arguments does us any good. In fact I would argue that if one takes into account sociological dynamics one presently has a lot of reasons to not trust researchers to be objective and unbiased which sheds much doubt on the use of these arguments.

Be that as it may, Dawid’s book has been very useful for me to clarify my thoughts about exactly what is going on in the community. I think his observations are largely correct, just that he draws the wrong conclusion. We clearly don’t need to update the scientific method, we need to apply it better, and we need to apply it in particular to better understand the process of knowledge discovery.

I might never again agree with David Gross on anything, but I do agree on his “pre-publication praise” on the cover. The book is very recommendable reading both for physicists and philosophers.

I wasn’t able to summarize the arguments in the book without drawing a lot of sketches, so I made a 15 mins slideshow with my summary and comments on the book. If you have the patience, enjoy :)

## 111 comments:

Dear Sabine, I agree with a big part of your remarks on this book and its content. But there are clear disagreements.

For example, it's just not true that the "no alternative argument" is a sociological one. It is manifestly an argument based on the evaluation of the actual, impersonal evidence that is available now. When it's done right, one may see that string theory has no alternatives.

What is sociological is the fact that not everyone can do it right. So there are people who haven't mastered what one has to master and who don't understand, or deny for other reasons, that string theory is the only game in town.

But exactly the same thing holds for every other scientific (or other) claim. There are always people who don't understand the science and who say silly things. But the photograph of the round Earth doesn't fail as "meritocratic" evidence in favor of the round Earth just because someone may yell that the Earth is flat, does it?

The kind of "sociologization" that you propose is utterly unscientific. You are implicitly asking scientists to be consistent with the claims by all other scientists - and perhaps all other people. But that's not how science works - or how it can work. A scientist must work (and evaluate the evidence) independently of the claims by others, so whether some people disagree can't have any impact on his answers to factual questions such as "does string theory have viable alternatives".

I don't agree that "Unexpected Explanatory Coherence" is a sociological argument. If I was the only scientist in the universe, and I was trying to explain X, but it turned out to explain X Y and Z, then I would have more justification that my model was not overfitted. It is a philosophical argument that happens to additionally have a sociological analog.

"

make sense out of trends in contemporary theoretical physics." Quantum gravitation, SUSY, and dark matter are mathematics not science (no empirical validation). Professionally managed physics specifically excludes falsifying experiments consistent with observation and falsifying curve fitting - they risk failure.Newton is rigorously derived, deeply validated, and wrong: GR, QFT; sychrotrons, Mercury's perihelion, stellar displacements near the sun's limb, Einstein rings...non-deterministic observation, entanglement, non-separability; Woodward-Hoffmann rules... The universe of quark matter is fundamentally

notmirror symmetric. Theory postulates it is, then parameterizes. failhttp://assets.sbnation.com/assets/2049377/maze.jpg

Elegant and rigorous.

http://i144.photobucket.com/albums/r200/Foglesby/US-Marine-Rat.jpg

Empirical.

Dear Lubos,

The no-alternatives argument should be an objective one, but it will not be objective as long as one tries to justify it by the 'we haven't found anything else' observation. Which inevitably has a sociological component because it rests on observing people's behavior. Now it might be that this behavior is an objective assessment of the actual situation. I just don't see any reason to believe that.

I have never, neither here nor anywhere else, asked scientists to be consistent with claims by other scientists. On the very contrary, my main concern is, as I have expressed frequently, that scientists don't disagree with each other sufficiently often. In any case, the point I am making is simply that we have no reason to trust the scientific system works towards objective theory assessment without studying this process. Indeed since you clearly have much faith that string theorists are totally objectively assessing their theory you should be in favor of such a study because it could be a strong support for string theory. Or do you have any doubts that the assessment is objective?

Best,

B.

Orin,

You're misunderstanding my point. The sociological aspect is that you have to believe your colleagues' intention (and execution of that intent). Look, consider such a requirement became an accepted assessment. I bet you suddenly physicists all over the place would find "unexpected coherence" just by claiming they had been looking for something different than they did. That just maneuvers you into an entirely murky corner of second guessing. Best,

B.

1. "No alternatives" is a weak argument for proposing the correctness of an idea.

(a) 'Best solution' is not 'THE solution'. Best is a statistic.

(b) It says more about the incompleteness of the existing coverage of our exploration of all possible ideas. i.e. if we've only explored 1% of all reasonable ideas, then we cannot argue that the pet idea we have found within that 1% is the best thing we will ever find.

2. I can offer a similar situation where 'no alternatives' is more solid: where you have two options or perspectives (often indicators of a duality), but make decisions to privilege one outlook over the other arbitrarily. Where one is de-selected for a good reason, you can say that your choice has 'no reasonable alternatives'. This is what the 'landscape' theories are lacking.

Sabine,

I agree there is a sociological aspect, but the one you describe is present for even the most canonically falsifiable areas of science. How can you trust a scientist's reported results? Well, you can reproduce the experiment, or work through a theoretical argument yourself. Similarly in Dawid's case if you don't trust the scientist you can work through the theoretical argument yourself and judge whether or not it was intellectually honest about aiming to explain X, but turning out to explain X, Y and Z. And that judgement is a philosophic one, not a sociologic one.

OK, Sabine, the statement "there is no other game in town" may have several meanings differing in the strength of the claim and the claimed evidence behind it.

The stronger one is that one has mapped the conceivable space of possible theories and showed that only the theories linked to string/M-theory are viable. While I don't think it has been done rigorously (and it probably cannot *ever* be done "completely rigorously"), I would argue that this has been done at the same level of confidence with which natural science normally settles questions.

But even if one doesn't have anything like a mathematical or physics-standard proof of such things, the claim about the "current knowledge" shouldn't be called sociological. At most, it's historical because it depends on the set of ideas available to the scientists at one particular point. But the claim is actually not meant to evaluate the people and their behavior. The claim is meant to say something about the space of conceivable theories which is a completely impersonal entity.

Some people are mixing these purely technical claims with politics and sociology but it's wrong, indefensible, and this harmful thing (politicization) could be done at *every* other place in science.

Similar comments apply to the "unexpected coherence" - I think that Orin meant the same thing. In the world of ideal science, there just shouldn't be anything sociological about these matters and it's the people who try to contaminate such arguments by politics and "sociology" who are harming science.

Why oh why the argument of unexpected explanatory coherence is sociological?

The fact that from the initial string "hypothesis" the theory leads you to introduce naturally dynamical D-branes and then from the bound system of D1/D5 D-branes you get the microscopic derivation of the Black Hole entropy area law is sociological??

No, of course not, this a highly non trivial technical fact. There is no sociology involved here.

I wonder if people still believe there is such a thing as 'The Scientific Method' ..

.. beyond the trivial definition 'what scientists do when they are at work'.

Dear Sabine,

thanks for the review! Let me just re-emphasise what has already been pointed out by Lubos and Orin in this thread.

The criteria of non-empirical theory confirmation are not sociological. They are based on observations about the research process. Scientists try to find alternative theories and one observes whether or not they find any. Scientists develop theories in order to solve specific problems and one observes whether or not those theories solve other problems they were not built to solve. Scientists trust their theories for some reasons and one observes whether or not those theories end up being predictively successful.

You are right that the process of dealing with those arguments in actual science is sociological and it is an important question to what extent sociological mechanisms affect the quality of the use of those arguments. The meta-inductive argument itself may actually be understood as one method of assessing this very question. If sociological mechanisms had often been responsible for suppressing promising candidate theories, or if they had been conducive to the generation of a flurry of fake ‘unexpected explanatory coherence’ arguments, theories that were trusted on those grounds more often than not would have failed.

I agree that the issue of the role of sociology is trickier with respect to deployments of non-empirical confirmation than in cases where conclusive empirical confirmation is to be had. Nevertheless it is important to distinguish the arguments themselves, which are not sociological, from their use in a community of human scientists, where the simple fact that human deliberation is involved brings in a sociological element.

If one does not make that distinction, empirical confirmation becomes sociological as well. We all remember recent differences among physicists interpreting empirical data. Someone who does not insist on a rational basis of scientific arguments even in contexts where sociological issues are at play could easily take those examples as evidence for the entirely sociological character of the scientific process. In fact, there is a position in the sociology of science that does deny that a meaningful distinction between an objective element in scientific reasoning and sociological processes can ever be drawn. That position calls itself the ‘strong programme’ (main exponents are David Bloor and Harry Collins) and defends a fully relativist perspective on science. If one rejects this relativist view of science, I see no reason for denying the distinction between rational argument and sociological issues in the case of non-empirical confirmation either.

1. Every true believer in a religion of the Book finds unexpected explanatory coherence in that religion.

2. Until the scientific method came along, every true believer in a religion of the Book was busy with the fratricidal task of making sure that there was no practical alternative. Today it is less bloodthirsty and is called proselytization.

3. Please note that "no alternatives" is not the same as a mathematical uniqueness proof.

4. Hypothesis pre-selection is a great saver of time and effort. But if we are going nowhere, the gates of hypothesis pre-selection need to be opened wider.

Giotis,

As I already wrote above, the sociological aspect is that it's presumably 'unexpected'. Look, I have no issue with the example in question in particular, this isn't my point. The point is that I can't see how to make such a requirement into a useful general criterion to assess the value of research results. Best,

B.

Dear Richard,

You write

"The criteria of non-empirical theory confirmation are not sociological. They are based on observations about the research process."Right, and what makes you believe that social dynamics plays no role in that? I am asking for the evidence...

"If one does not make that distinction, empirical confirmation becomes sociological as well."It does have social effects, and some of these are well documented. But the way the system is set up right now these effects aren't particularly pronounced, and I am not very worried about them. If you want to say that on the experimental side too one should make sure that social effects don't play a role, I would totally agree with that.

Besides, the meta-inductive argument is the one I have the least problem with. It clearly has a non-sociological component and its success is reasonably well documented in the history. The other two, well, I just don't see what evidence we have to conclude these are good criteria. I am not saying these aren't criteria that aren't used. Neither am I saying they are necessarily bad criteria. I'm just saying I don't see the ground on which to trust them.

Best,

Sabine

Dear Lubos,

You write

"In the world of ideal science, there just shouldn't be anything sociological about these matters"That's right. But we don't live in an ideal world. For this reason you cannot just discard sociological effects. It's sad but true. All I am saying is that it's an added uncertainty and that to trust Richard's claims one would have to understand how large the systematic errors and uncertainties from sociological effects are. Best,

B.

I would accept "the only game in town" argument if there were even one game in town. But surely nobody any longer seriously believes that string theory has successfully quantized gravity. If it has, then pray tell us what happens at spacelike singularities. The usual formulation is that "string theory is not well understood in these cases [ie, all of the important ones]". Fine, but then don't claim that you have a "game" [yet]. To me, "X-theory is not well understood in circumstances Y" is not distinguishable from "X-theory has so far failed to explain Y".....

Lubos,

"The stronger one is that one has mapped the conceivable space of possible theories and showed that only the theories linked to string/M-theory are viable. While I don't think it has been done rigorously (and it probably cannot *ever* be done "completely rigorously"), I would argue that this has been done at the same level of confidence with which natural science normally settles questions."

This is an outrageous claim. Could you please give some reference(s) allowing one to follow this argument.

Markus If you take as true the simple assumption that a Theory of Everything must be a theory of Quantum gravity then indeed there are no alternatives to String theory.

Since it is the only theory that:

- Unifies QM and GR by successfully quantizing Gravity in a consistent way

- Correctly reproduces the Bekenstein-Hawking entropy S = A/4G by summing

over states

- has GR as its limit at low energies

- It is UV finite

- Has no dimensionless free parameters

- Naturally incarnates the holographic principle

- Provides the only known solution to the Cosmological Constant problem

- Naturally incorporates Super-symmetry and Super-gravity

- Naturally gives rise to chiral matter, scalars, Non Abelian gauge groups and

GUTs

- Explains the properties of a vast number of QFTs in a fundamental way via their Stringy realization

- Gives rise to deep unexpected physical insights like dualities

- Incorporates every promising theoretical idea from non commutative to Higher spin theory

- Gives rise to highly non trivial results in QFT like the 6d (2,0) SCFT.

- Gives rise to deep unexpected mathematical insights like Mirror symmetry

- Realizes from physics point of view deep mathematical conjectures and symmetries like the Geometric Langlands correspondence and the Monster group

Giotis, if it is so good, why isn't it more widely accepted?

Has string theory made any testable predictions which differ from other theories? If not, it is not a valid theory. If so, but they cannot be tested any time soon, then it might be a valid theory, perhaps even true, but not useful.

However, one can never say that it is the only game in town. There might be others which we haven't yet discovered.

- Unifies QM and GR by successfully quantizing Gravity in a consistent waySo does asg, lqg, and I don't think cdt would have any problems with putting fields on space-time either, it's just a matter of time. As the saying goes absence of proof (that other approaches can do it too) isn't the same as proof of absence.

- Correctly reproduces the Bekenstein-Hawking entropy S = A/4G by summingover states

You are referring explicitly to the microscopic interpretation. If a theory has qft in curved space as a proper limit it must give rise to the BH entropy, we already know that. The microscopic state counting that string theory adds to the picture? Well, we don't know whether that's correct - correct in the sense of actually being realized in nature. This isn't a "correct reproduction" it's an untested (and probably untestable) prediction.

- has GR as its limit at low energiesSo does asg.

- It is UV finiteSo is asg (claimed to be).

- Has no dimensionless free parametersExcept that you then have to come up with a mechanism to get all the other parameters in the standard model back and, not being able to deliver, string theorists have then just declared that it must be anthropic selection. Which really doesn't explain anything.

Besides this, as I've explained elsewhere, I don't understand what's the big deal with assuming numbers. Every theory is based on some assumptions that have been picked from an uncountably infinite set of assumptions. Adding some number is just one of them, and I don't see how it's any better or worse than, say, assuming Lorentzian signature or absence of anomalies, or Dirac quantization, or the path integral formulation, or locality, and so on and so forth. So I fail to see how that speaks for a theory.

- Naturally incarnates the holographic principleWhich has been argued to be a general property of quantum gravity (not saying this is correct). And in any case, we don't know that this is actually a correct description of nature, so who cares?

- Provides the only known solution to the Cosmological Constant problemAnd that is?

- Naturally incorporates Super-symmetry and Super-gravityWhich might be more convincing had one actually found some evidence for susy.

- Naturally gives rise to chiral matter, scalars, Non Abelian gauge groups andGUTs

I would settle for getting the standard model...

- Explains the properties of a vast number of QFTs in a fundamental way via their Stringy realizationYes, that's very interesting, but what does this tell us about string theory as being the theory that unifies the SM with gravity - in our universe?

- Gives rise to deep unexpected physical insights like dualitiesRight. But again, why is that relevant for its prospects of being a unification of SM and gravity?

- Incorporates every promising theoretical idea from non commutative to Higher spin theoryThat's great, and somewhere in the multiverse it maybe describes actual observations, but as long as it doesn't describe our universe any better than the SM & GR, why is that relevant for its prospects of being a unification of the SM and gravity?

- Gives rise to highly non trivial results in QFT like the 6d (2,0) SCFT.Nice. Why is that relevant for its prospects of being a unification of SM and gravity?

- Gives rise to deep unexpected mathematical insights like Mirror symmetryYes, interesting. But why is that relevant for its prospects of being a unification of the SM and gravity?

- Realizes from physics point of view deep mathematical conjectures and symmetries like the Geometric Langlands correspondence and the Monster groupAnd again, why is that relevant for its prospects of being a unification of SM and gravity?

It is widely accepted.

All top universities and Institutes (especially in North America which sets the tone of contemporary hep-th research) and the vast majority of the top physicists working in them have adopted the string theory paradigm and are active researchers in the field.

Of course there will always be people working on the fringe, you can’t avoid that.

Giotis said: String theory is the only one that "Unifies QM and GR by successfully quantizing Gravity in a consistent way."

Well, you see, this is where the sociology comes in. Because it is a matter of sentiment whether string theory "successfully" quantizes gravity. And, by the way, the overwhelming sentiment in the community [see the arXiv, any day nowadays] is that this statement is not correct. How many papers begin with, "Absent a quantization of the gravitational field, we are forced to....." ?

The list of claims you have made has been around for decades. Nobody is buying it any more; worse, young people find all that totally boring. Time to ask yourself what that means.

"It is widely accepted.

All top universities and Institutes (especially in North America which sets the tone of contemporary hep-th research) and the vast majority of the top physicists working in them have adopted the string theory paradigm and are active researchers in the field."

Argumentum ad populum. That's why I'm saying it's sociology. Sociology combined with bias and logical fallacies. Sorry, Giotis, I much respect your knowledge about string theory, but so far you haven't made a very strong case.

Sabine I was just answering Helbig's question:

"if it is so good, why isn't it more widely accepted?"

Giotis,

Sorry, I thought it was a reply to my comment.

String Theory "Naturally incorporates Super-symmetry and Super-gravity" --- IMO, this is the closest String Theory has come to being scientifically testable. If LHC doesn't find super-symmetry, yes, String Theory can be tuned to have its phenomenological derivations to not reveal super-symmetry, but I think this will be considered in some way unnatural and string theory will go the way of the luminiferous ether as a means of explaining the world. (It will remain for the mathematics.)

Sabine, regarding your comments.

I was referring to the general ingredients a candidate ToE (or framework if you like) must have in order to justify its name.

A complete “Cosmology” that will match (and explain) our effective universe as we understand it (SM+GR+ a cosmological model) is still missing but the theory is under development.

The aforementioned ingredients though indicate that String theory is the only theory that has potential to achieve this goal.

Markus, were you joking when you used the word "outrageous"? It is a wording that the Inquisition insisting on geocentrism wouldn't be ashamed of.

In science, claims are not "outrageous". They are just right or wrong. My claim - despite the impossibility of making it quite rigorous at this point - is certainly closer to "right".

Yes, of course, there are numerous technical papers proving, with some internal assumptions, that string theory is the only game in town. Look e.g. at this blog post that links to 2 papers by Maldacena et al., and papers by Rangamani et al., Maloney et al., and Veneziano et al., plus a popular recent review of these papers in the Quanta Magazine.

If you have read my blog regularly, you would know about lots of other proofs and papers in this direction, not only mine, e.g. about the reasons why the maximum supergravity has to be completed to M-theory on 7-torus to be consistent, and many partial proofs of the statement I made.

Many proofs are "partial" because they show the uniqueness of string/M-theory in some "corners of the landscape of quantum gravity backgrounds". What's missing is a universal proof, but that's to be expected because we don't have the most general definition of string/M-theory, either. We cover this theory by "patches" like a manifold, and we know "lots of these patches".

The right description isn't that my claim is "outrageous" but you, due to your clear complete ignorance of all this research, are completely inadequate for a discussion on foundations of formal theoretical high energy physics.

Giotis,

That string theory has given rise to all kinds of interesting mathematical relations is for all we can tell entirely irrelevant for its prospect as the theory of quantum gravity (in our universe, as opposed to 'a' theory of quantum gravity), so to me this is just producing fog by which string theorists hope to awe people and to get funding that would otherwise go to real science.

We have no grounds on which to conclude that a candidate ToE must give rise to mathematically interesting relations (and that's leaving aside that 'interesting' is a subjective term). The same goes for often named qualifiers - I note you restrained :) - like elegance, beauty or simplicity, though you did bring up the parameters.

Asymptotically safe gravity seems to me like the most depressing option possible, and I kind of hope that's not it, but it does all we've asked for. Maybe nature's mathematics isn't all that terribly inspiring and maybe quantum gravity isn't all that pretty a theory. Why should that be so?

For that reason, your belief that the 'aforementioned ingredients' indicate that 'string theory is the only theory that has the potential' to unify the SM with GR is just doesn't follow.

You see, it's not that I don't like string theory or don't think it's interesting or that the points you have made are not correct. I just don't see how this matters for finding a correct description of nature.

Oh, and the cosmology. In the end it comes down to the question where the initial conditions come from. I don't expect a theory that unifies the SM & GR to do that too.

Best,

B.

Giotis,

nice list, thanks. Let me very quickly (and superficially) go through it and make some (non-expert) comments.

- "If you take as true the simple assumption that a Theory of Everything must be a theory of Quantum gravity".

I doubt, Fermi gamma-ray space telescope and Dyson say sth. else.

- "Unifies QM and GR by successfully quantizing Gravity in a consistent way."

You mean it is mathematically consistent ? Unfortunately nobody really seems to know what exactly the theory (actually M-theory) is.

- "Correctly reproduces the Bekenstein-Hawking entropy S = A/4G by summing over states."

Fine, but many theories of QG do so (e.g. LQG). Moreover this formula is not experimentally backed so far.

- "has GR as its limit at low energies".

Yes, but also additional terms which need experimental verification.

- "It is UV finite".

Yep, I think this is one of THE strengths of string theory.

- "Has no dimensionless free parameters."

This can also be seen as bad in this case because it bans one for instance to an unphysical number of dimensions.

- "Naturally incarnates the holographic principle".

Why would we need this principle in the first place ?

- "Provides the only known solution to the Cosmological Constant problem."

Come on, are you joking, what should that solution be (references please)?

(I actually know of only one computation of Lambda which however is not string inspired).

- "Naturally incorporates Super-symmetry and Super-gravity".

Which probably will never be found in experiments :-)

- "Naturally gives rise to chiral matter, scalars, Non Abelian gauge groups and GUTs"

Bla, bla, all it takes is to reproduce the Standard Model in the first place which ST doesn't. In fact Connes derives it from first

principles of NCG in nearly a unique way. I therefore regard his theory currently as the TRUE "only game in town" when it comes to the right

approach to a TOE.

- "Explains the properties of a vast number of QFTs in a fundamental way via their Stringy realization."

Most of them probably unphysical. How do you pick the physical ones ?

- "Gives rise to deep unexpected physical insights like dualities."

Why are they physical and not just purely mathematical?

- "Incorporates every promising theoretical idea from non commutative to Higher spin theory".

Let me answer this with a quote by Ingemar Bengtsson: "One can probably prove a theorem to the effect that string theory has an ergodic property

that will make it come arbitrarily close to any point in idea space, if one waits long enough."

- "Gives rise to highly non trivial results in QFT like the 6d (2,0) SCFT."

Purely mathematical as we live in 4d.

- "Gives rise to deep unexpected mathematical insights like Mirror symmetry"

Nice mathematical results, indeed.

- "Realizes from physics point of view deep mathematical conjectures and symmetries like the Geometric Langlands correspondence and the Monster group".

I don't see what the physics point of view is when ST "hijacks" yet another deep field of pure maths with beautiful preexisting results.

IMHO any good theory should go through 3 phases:

1) Set up a mathematically consistent theory. (ST maybe be at least partially successful in that).

2) Reproduce the known physics (ST badly fails here, e.g. SM, de Sitter space).

3) Make new predictions (ST makes many many predictions, but not a single one which has been verified so far).

Best

Sorry, Sabine, but string theory's ability to produce the mathematical relations isn't irrelevant for its being the right theory of quantum gravity.

It is relevant and it is pretty much what the "unexpected explanatory coherence" - using Dawid's language - is all about, too.

Why is it relevant? Every time one finds a relationship - let me talk about a string duality, to be specific, but the remark applies to more general mathematical findings - the coverage of the space of potential ideas or theories by string theory gets doubled (or multiplied by a greater N) and all these equivalent descriptions become more robust at the same moment.

It is a general feature of correct theories in physics that they may be described by many, in string theory's case not manifestly equivalent, formalisms and from many viewpoints.

Take non-relativistic quantum mechanics. It may be described in Schr. and Heis. pictures, Dirac interaction picture, by Feynman path integrals, with Hamiltonian or Lagrangian playing a central role, and reconstructed from various limits, like the classical limits, or as solutions to sets of constraints involving conservation laws and other things. A small number (S) of assumptions may often reconstruct the theory almost uniquely, and there are many (M) starting points how to do it. The smaller S is, the more likely the theory is. And the greater M is, the more likely the theory is, too.

This property of quantum mechanics is undoubtedly a part of the certainty that it was and it is a theory on the right track. It's like looking for the most important town on Earth, and finding a city into which many roads lead. Well, if that's so, it's probably because it's Rome, indeed, and all roads lead to Rome.

A city that has many or all roads going into it is qualitatively different from a generic city that fails to obey this property, and that's why it should be given a higher prior probability of being correct (more generally, of playing the "special role" of being the only correct one among many wrong ones). In other words, the assumptions "the most important city in the world is a city into which all roads lead" and "the most important city is one of the thousands of towns into which not all roads lead" should be considered comparably likely because they're two qualitatively different hypotheses.

So it's significantly more likely for Rome to be the most important city in the world (2 millenniums ago) than for a generic non-central town.

The situation is analogous with quantum gravity. All the mathematical relationships are really roads that lead to the Rome of string/M-theory from other sensible places.

The existence of roads has no special relationship with "quantum gravity". One must determine that string/M-theory is viable as a theory of quantum gravity by looking into its actual properties and predictions. But the existence of the many roads increases the string theory's probability of being the *right* theory for whatever purpose it hasn't been falsified yet.

The arguments above are completely factual, not sociological, and they really represent "Occam's razor done right". Whenever a duality or another mathematical relationship is found, one *reduces* the number of mathematically/logically inequivalent assumptions, axioms, or basic building blocks that string theory is based upon, by identifying them or unifying them. Equivalently, one increases the prior probability of string/M-theory because he sees that several/many theories derived from some starting point that used to be thought to be inequivalent are actually equivalent.

(I could use an example involving 3 copies of damn sushi in an obnoxious recaptcha code that look just like icecream, soup, steak, or pasta, but those things are too annoying so I prefer to pick other examples LOL.)

So if one had some mathematically sharp way to quantify the "truly relevant" number of mathematically inequivalent assumptions, axioms, and building blocks that quantify how much a theory is "contrived" or "randomly constructed", due to the dualities and other mathematical relationships it produces, string theory would be seen to be in a vastly better shape than the theories that don't produce such relationships or dualities.

One can misunderstand "why this argument works" at the Bayesian level sketched above but she should still be able to see that this property - the ability to produce some interesting new mathematical relationships or make some portions of mathematics "relevant" - was the property of all major revolutions in physics, so it's sensible to expect that the next revolution in physics should have this property, too.

Lubos,

How many interesting relations you have found within a theory depends on the amount of work you've put into it (read: people working on it), not to mention on the question what one finds interesting. The same goes for the 'roads' that have been found leading to this theory.

Thus the arguments 'look, nobody has found anything more interesting' and 'we've found so many roads' are worthless as long as I can't be sure whether that's due to there not being anything to find (science) or not enough effort having gone into it (sociology).

I think there is a certain realization of a acceptance of transcendence, in face of recognizing the Universals. It is a philosophical argument that can be assigned to a top down use in the square of opposition.

In recognition of this process then, one could assign string theory and the basis of the form of the good and what beauty means, as the philosophical recognition of the Platonist comes into view? You might have to ask yourself are you a Platonist and I did, so as to examine what is going on in the science of this exchange.

Best,

"The criteria of non-empirical theory confirmation are not sociological. They are based on observations about the research process."

This epistemological framework proposed by Dawid and others is reminiscent of classical Greek ontology inwhich abstract thought was considered superior to the empirical method of obtaining knowlege. This approach is retrogressive and unscientific to say the least. If a theory can neither be tested nor confirmed it serves no practical use for humanity and will inevitably be relegated to the dust bins of history. Pursuing this approach would be a terrible waste of financial and human resources that should be deployed to more promising approaches such as phenomenology among others.

Sabine, it's simply not true. This silly comment of yours is just another example that you try to convert everything to sociology.

Even if millions of Smolins were working on loop quantum gravities and spinfoams and dynamical triangulations and conformal gravities in d=4 for millions of years, they would never find any relationship that is comparable in its depth, universality, and importance to mirror symmetry or other dualities of this form simply because LQG and other superficial cheap ideas simply don't contain any similarly interesting mathematics in them.

This is an objective mathematical, not sociological or historical, fact.

"

Holt quotes from Einstein, "How can it be... that mathematics, being after all a product of human thought independent of experience, is so admirably appropriate to the objects of reality?"There is a perception here about the question of Realism?

Lubos,

sorry, my wording was really bad - advanced tiredness, you know ...

Thanks, for the references. It'll take me a while to go through them, so I'll not further comment on the issue here.

Yes, your Blog is a good source, but unfortunately my reading pace comes nowhere close to your writing pace, so I probably miss a lot.

Best.

Who needs predictions when one is in the guaranteed possession of The One True Faith?

Empirical testing is so messy and old school.

Lubos,

"Even if millions of Smolins were working on loop quantum gravities and spinfoams and dynamical triangulations and conformal gravities in d=4 for millions of years, they would never find any relationship that is comparable in its depth, universality, and importance to mirror symmetry or other dualities of this form simply because LQG and other superficial cheap ideas simply don't contain any similarly interesting mathematics in them.

This is an objective mathematical, not sociological or historical, fact. "

Oh, really? And it's objective because you say it is? That's an interesting argument. If it's a mathematical fact, then why don't you go and prove it.

I have written many times that we don't have a *rigorous* proof of such propositions.

But these propositions are objective because they're not matters of opinions, like the question "these and those taxes are good or bad for the people". They are propositions about objective matters.

These particular statements are statements about questions that don't depend on the right theory of Nature at all - they are about mathematical properties of theories. That's what it means to say that they are *mathematical* facts.

The evidence is overwhelming that my statements are right - it is about our sufficiently advanced mapping of all relevant mathematical structures. You are only suggesting that my statements are not right for purely egotist reasons - and you can do so because you know that there are lots of *totally* ill-informed people among your readers.

But you and these people can't change the fact that my statements are right.

Lubos,

You are really trying to argue that we have mapped "all relevant mathematical structures"? I suppose we can close the departments of mathematics then and ring in the end of science. Let's call Horgan to join the party.

"These particular statements are statements about questions that don't depend on the right theory of Nature at all - they are about mathematical properties of theories. That's what it means to say that they are *mathematical* facts."Which just means that even if it was right what you said it still wouldn't matter for finding a theory that describes nature at the fundamental level.

I wrote that we have achieved a sufficiently advanced mapping of the mathematical structures relevant for the behavior of known descriptions of string theory and known and previously proposed alternative directions and theories of quantum gravity such as loop quantum gravity.

This doesn't mean that we have learned all of mathematics. Mathematicians are doing tons of things in many directions and most of them have no implications for physics. After all, the mathematics departments' contribution to the enterprise I mentioned – understanding of the mathematical structures relevant for the formulation of the deepest laws of physics – is extremely small these days, so by closing them, one wouldn't harm the business much, either.

You: "Which just means that even if it was right what you said it still wouldn't matter for finding a theory that describes nature at the fundamental level."

No, as I have already tried to explain to you – but it is clearly totally hopeless to try to explain *anything* important to you – mathematical properties of a physical theory or hypothesis are *always* extremely important for its fate and for its probability to be correct. Your idea that "because it's mathematics, a physicist can just ignore it" only highlights your complete inadequacy as a theoretical physicist.

Lubos,

Needless to say, I never even remotely said that physicists can just ignore mathematics. I merely said that you haven't come up with any criterion for string theorists' selection of mathematics that is supposedly relevant to describe nature that actually matters. Your argument basically can be summed up as "people like me think it's interesting therefore it must be relevant to describe nature". That, I'm afraid, doesn't count as a scientific argument. Best,

B.

Lubos,

I strongly agree with your comment "mathematical properties of a physical theory or hypothesis are always extremely important for its fate and for its probability to be correct".

Although my background as a postdoctoral fellow is nonlinear dynamics and statistical mechanics, in my eagerness to learn always more mathematics, I have devoted myself recently to the study of string theory, intrigued by the many wonderful results it has contributed to mathematics.

You usually cite "mirror symmetry", but I also celebrate the feat achieved by R. Borcherds in proving the "Monstrous moonshine" that, quite surprisingly relates the modular j function to the Monster group thus joining two branches of mathematics that apparently had nothing in common. In the magnificent proof of the theorem a crucial step is made by invoking the "no ghost theorem" of string theory.

These facts cannot be appreciated by these 'sociologists' who like to write opinionated books against things that they cannot grasp. In general, our time hates mathematics, society as a whole is not interested in mathematics/theoretical physics, and we witness a strong regression in everything concerning human thought. But the truth will prevail at the end and it requires from those who seek it patience and hard work: the joy of having something consistent with which we can work with, is already something to be thankful. Let opinionated folks just waste their time writing opinions and let scientists rejoice doing science!

Cheers

Sabine,

the criticism "you haven't come up with any criterion for string theorists' selection of mathematics that is supposedly relevant to describe nature that actually matters" has no validity at all. Vertex operator algebras have been inspired by string theory and one can only envisage that they shall be to XXIth century what Lie algebras have been to XXth century. There is also mirror symmetry, Connes' noncommutative geometry, knot polynomials... And many things that are valuable in mathematics have been incorporated in string theory. String theory not only contains beautiful and consistent ideas and working hypotheses: it provides tools with which one can work with, and this is the most important thing.

There is one aspect of the "only game in town" sociology that everyone ought to consider, namely: if there is only one game in town, could it be that there are many people working on string theory who don't actually believe in it? I think that there are many such people. You know, they say that Mother Teresa, soon to be a Catholic Saint, was actually a covert atheist, and of course there are many "religious" people like that. The way to detect them is as follows: they *pretend* to be fanatical believers, in order to conceal their doubts from others -- and perhaps themselves.

Come on, Lubos, confess! It's all bullshit, and tired, boring bullshit at that, and you know it. You know you want to confess your sins: this is the time and place to do it!

Hermannus,

Yes, you are right, that was not a good statement. As I had made clear earlier, I was referring specifically to the promise of string theory as a fundamental and unified theory for the standard model and gravity in particular, and not to its use for the description of nature in general. Best,

B.

Sabine,

I do not understand your criticism because I see string theory as a very plausible candidate for a fundamental and unified theory for the standard model and gravity. Reasons:

- One starts from a very elegant ansatz with a minimum number of assumptions and you get a lot, consistently, from this ansatz.

- For example, you have the graviton, a spin-2 particle as a NECESSITY coming directly from the theory. This is a most remarkable, unavoidable, and wonderful fact.

-The standard model structure SU(3)*SU(2)*U(1) can be also embedded so that you have also Yang-Mills there.

- You do not have freely adjustable parameters

- You do not have any catastrophic divergences anymore

- It is true that you have a lot of new degrees of freedom but this in turn means a lot of new physics and mathematics and a lot of enjoyment

- Since you have more dimensions than four you can also pose the interesting and deep question of why there appear to be only four dimensions directly to our experience. To say that the other dimensions are not there because we do not see them is unscientific. In principle, everything that is a solution to an equation motivated by physics can be there and one has to seek.

- The powers of the abstraction of the human mind lead to the conception of mathematical structures such as Calabi-Yau manifolds so as to explain compactification of these additional dimensions. The investigation of these structures, together with vertex operator algebras and many other things, are worth the effort in themselves and opens new paths for exploration in physics and mathematics.

- Although many physical claims made in string theory may prove to be wrong, most of the results will survive in some form because mathematical truth belongs to eternal truth, and soon or later finds application to the nature 'that matters'.

- If supersymmetry does not appear at the end, this is because the generosity, beauty and goodness of God has no limits and something even better is reserved for those who seek the truth honestly and humbly. In fact, the 'tragedy' of not finding SUSY should also be a rare enjoyment for those minds.

Folks which merely strive for human recognition (according to our human weakness and need of 'feeling good and useful') cannot comprehend this. The joy of understanding something deep that is experienced by those who work hard not for their own reward but for the sake of the truth, is alien to them.

Best regards

While I have hoped to help some understand beauty in its right context, the understanding of "pure states" it is of relevance as too, how a Platonist sees. Any of you might even realize you are one.

This understanding is current and important to the philosophical question here as we moved forward in this century.

Pure states are "states of beauty" for all intensive purposes, these realizations were mathematically based in abstraction, but now, these pure states in the philosophical jargon, are real?

You know I have been around a long time Bee and have been trying to explain myself......I certainly hope this has become much clearer now.:)

Best,

One way to articulate Lubos's comment is to say that string theory is part of "moduli space of theories" which includes the standard model of particle physics. Upon considering controlled deformations of the standard model, and applying confirmed dualities, we can derive the existence of a relativistic quantum theory which includes gravity. This is string theory.

The above statement is not sociological. It is pretty much a mathematical statement, and will continue to be true regardless of what any particular person thinks. It will even be true regardless of whatever approach to quantum gravity turns out to be right. The existence of string theory of course does not imply that it describes our universe. But the fact that it is connected within a tested framework to theories we know to be true is difficult to dismiss.

I do not think that, based on current knowledge, a similar claim can be made for any other approach to quantum gravity.

Dear Hermannus, thanks for your agreeing reply! The importance of mathematical virtues for the laws of physics isn't such a controversial thing. On his 1955 trip to Moscow, Dirac was asked to summarize his philosophy of science so he wrote a capitalized sentence on the blackboard, "Physical laws should have mathematical beauty".

These days, one could almost feel like a heretic for sharing similar views that were so important for many key figures of the 20th century physics.

I actually consider the monstrous moonshine *deeper* than mirror symmetry, too! It's just that the string theory-like equations that explain the moonshine are further from the "observable physics" - wrong numbers of large dimensions etc. - and that's why I sometimes pick mirror symmetry that is directly relevant because the same Calabi-Yaus that exhibit it are vital for realistic string vacua, too.

"Let them do that, let them do that" sounds fair and nice, except that the very purpose of these external assaults on contemporary theoretical physics is "not to let" the theoretical physicists do what they're doing, and this anti-science movement has quite some success.

Dear Rastus, I am confident that there are numerous people who are doing string theory while "not believing it". I can't be quite sure about any particular name although I have observed these feelings in some people I won't name.

I can tell you particular names in the case of supersymmetry phenomenologists. Adam Falkowski had co-authored numerous papers but I think that he has never "believed" supersymmetry.

It seems clear that one cannot get too far while not believing "it". An intelligent enough person may survive but not really "make a difference".

It is not quite possible to "prove" that someone is an opportunist of this kind, and even if it were possible, I doubt it would be "wise" to punish the people for that attitude simply because even they can make some advance.

There are "opportunists" in all other fields that flourish. For an extreme example, I know that there are creationists who are doing a pretty good research in mainstream genetics or even evolution. It can happen. As long as their work is being evaluated fairly and meritocratically, it can simply happen that they "make it" despite their unexpected credentials.

Concerning your request "repent", I won't. I always have doubts about anything that isn't quite solidly proven but my certainty about the need to use string theory as the framework to describe Nature including quantum gravity is comparable to my certainty about the existence of other galaxies - and probably higher than my certainty about the existence of dark matter.

The number of "critics" of string theory who don't believe their nonsensical criticisms is surely by many orders of magnitude higher than the number of string theory disbelievers who could make it to string research. Well, the number of such dishonest critics is really higher than the number of all string theorists in the world, anyway. Critics are cheap, research is not.

Tchovi,

Right, I agree with this. But science is about describing our universe, and as you correctly observe that it contains *a* theory of quantum gravity doesn't tell us it is *the* theory that is actually correct, in the sense of describing nature. Thank you for the nuanced comment though. Best,

B.

Hermannus,

I find it peculiar that you and apparently other people think I am "criticizing string theory", whereas I am instead criticizing a book by a philosopher about changing the scientific method. I have no problem with string theory in particular. As I have now said several times, I totally agree that it is "a plausible candidate". There are other plausible candidates too. What I am saying is that the three arguments raised in the book are not on solid ground as long as one doesn't account for sociological factors that play into the suggested assessment.

The reasons that you mention, as pointed out before, are arguably all properties that people find appealing about string theory but from this it doesn't follow that it's the correct unification of the SM and gravity. Best,

B.

Sabine,

You say that you are not criticizing string theory but then you add that there other candidates too. What are these other candidates? And I mean, serious candidates that can match any of the points that I have given above and which you seem to underestimate as something that "are arguably all properties that people find appealing about string theory". Well, I find that your statement is pointless. If you are discussing about gravity and about the standard model then you should look for a theory that strives to describe the properties which concern quantum gravity and the standard model.

I am a detached observer, with a professional background in Physics, who is eager to learn. And from my own findings and my own unbiased judgment, I must inform you that I do not find any alternative to string theory: loop quantum gravity is certainly not. One cannot simply compare the book by Rovelli on quantum gravity, with the ones by Polchinski, Zwiebach or Witten & Co. While it is clear to me what the string theorists are doing (not without hard work) I find LQG inconsistent and sloppy. Many statements in the book by Rovelli are naive to me, devoid of any mathematical substance, and cannot be taken seriously. If , however, you read Polchinski, everything that is promised in the introduction, is then shown to be mathematically true. As a detached observer I then choose Polchinski as starting point for my own questioning. I think this should count as something of 'sociological value', as the input from a person who is detached and who can appreciate what is under discussion.

Sociologists present as candidates some theories that have not the dignity to be called 'proposals' and that rather belong to 'fringe science'. To put these on the same foot with string theory is analogous to say that in Auschwitz jews were not killed because there were a couple of SS officers that were sympathetic to them: To speak of any other candidates in this discussion, in the light of evidence, is to deny string theory.

Furthermore, I must say something about the dishonesty that those popular books as "Not even wrong" represent. They pressupose that scientists cannot assess individually the value of a theory and there are sentences that suggest, for example, that most string theorists are doing string theory 'because this is what Witten, the genius, does'. This 1) pressupposes that most of those smart individuals that work on string theory are not able to judge individually on what they are doing and that they are somehow 'hypnotized' by the strongest figure; 2) merely singles out Witten as the genius of our age and, with this strategy, makes him as someone with all responsibility on his shoulders (as if he were the guru of a sect). I find all this very dishonest and insulting.

Wittgenstein already warned of those books on 'popular science': They create the illusion that laymen can simply 'understand' deep things without the work and concentration they require, and they usually entertain the idea that things that are deep and complex belong only to an elite that is also well paid and economically powerful. This is a crime, and here again I can only agree with Lubos, because it distracts the attention of the intrinsic scientific value of what these people have achieved, and because it amounts to reduce the hard work of many anonymous people to nothing.

Each individual can choose, whether to do science, or to entertain those sociological ideas for the sake of personal profit. If you question things radically, you should not only ask why string theory has been adhered to by most prominent physicists and mathematicians: you should truly understand what you are talking about, and go through the hard work of the theorems that have been derived, the problems that have been tackled, the ones that remain. Then, hopefully, you will learn to estimate the value of what has been accomplished.

Best.

Well: Feynman path integral method, which works very well, si not mathematically consistent in any way ( see: http://mathoverflow.net/a/56710/3811 ). It may be considered only as "interesting calculation without rigorous definition" - just like Euler proof for 1+2+3...+ oo = 1/12

Maybe You do not know/remember but at the very early days of Quantum mechanics, there where nearly no mathematics needed for it, and many theoretical physics geniuses in fact created a big part of contemporary mathematics for description of "non-commutative probability theory" for quantum mechanics. So "mathematical consistency" is just aesthetic criterion...

Hermannus,

"You say that you are not criticizing string theory but then you add that there other candidates too. What are these other candidates?"I find it interesting that you evidently rate it as a "criticism of string theory" to merely mention the existence of other approaches to quantum gravity.

As I mentioned several times above and also in my video, for all I can see asymptotically safe gravity is a plausible and reasonably promising, though ultimately somehow depressing, approach to unify qft and gravity.

For what LQG or CDT or Causal Sets are concerned, these aim primarily at quantizing gravity, and the question of bringing in matter fields is somewhat secondary. As I said above though, absence of proof isn't the same as proof of absence. If you think it is, look up "jumping to conclusions" under "logical fallacies".

Besides this, unless you believe (of course you do) in the no alternative argument that's totally irrelevant.

You are terribly mistaken if you think I am criticizing string theory because of my criticism of Dawid's argument that the scientific method should be altered. I am merely trying to find a rational basis for the belief in string theory that seems to be fairly wide spread. Unfortunately I cannot find one, and Dawid didn't provide it either for the reasons I have elaborated on. I don't know what makes you think that string theory must be the right theory to unify GR and the Standard Model.

"Sociologists present as candidates some theories that have not the dignity to be called 'proposals' and that rather belong to 'fringe science'. To put these on the same foot with string theory is analogous to say that in Auschwitz jews were not killed because there were a couple of SS officers that were sympathetic to them: To speak of any other candidates in this discussion, in the light of evidence, is to deny string theory."Firstly, I don't know what you mean with "fringe science", other than that you might mean there are fewer people working on it than there are on string theory.

If your crude analogy is supposed to say that there are more people working on string theory, then yeah, that's arguably true. Now what exactly does this prove, that's the question I am asking you?

If I had reason to trust in academia to give incentives to scientists to make objective judgments, then this would speak in favor of string theory. However, I have very little reason to have this trust seeing how academia works today.

Oh, yeah, I have personal opinions about all these matters, as you do and as everybody has. The question is, how are these personal opinions integrated in the dynamics of the community, and how much are they influenced by social effects.

Your dismissal of the presence of social effects and of the influence that popular authority figures can have highlights the problem very nicely. You, as many scientists, believe that you are so totally superior and so awesomely intelligent that you cannot possibly have any kind of bias, that you cannot possibly be influenced by the way information is communicated to you, and by the options you are given to receive of it. You somehow believe that string theorists are immune to sociological effects that have been demonstrated in the literature over and over again. There is even a word for it, it's called the "bias blind spot".

What I am telling you is simply that as long as we, as scientists, are not properly accounting for our own biases, we're not doing good science. Whether accounting for our biases would change anything about the popularity and assessment of string theory, I don't know. Best,

B.

Sabine,

Ok, thank you for the tip about "asymptotically safe gravity". In fact the UV fixed point is also mentioned in Polchinski's book in the introduction as an 'alternative', but no longer discussed. I will have a look to this. I do not find any of the other things you mention, LQG, CDT and Causal sets, neither interesting nor serious.

You say: "I am merely trying to find a rational basis for the belief in string theory that seems to be fairly wide spread." Of course, the trivial ones based on mathematical soundness, the elegance, simplicity and sophistication of the approach, the richness and possibilities that are opened, this does not seem to tell anything to you. For you, the existence of theorems and rigorous results seems to amount to nothing. My conclusion is that you are then seeking not arguments, but a confirmation of what you want to hear.

With 'fringe science' I did not mean that there is few people working in it, but that the approaches are scientifically mediocre as to be considered valid proposals. A valid proposal is something that is closer to the truth because it consistently incorporates well established truths. With my crude analogy (so crude, I am sorry) I meant that those historians who deny the Holocaust based on stupid arguments do not deserve to be called historians (neither to be tolerated as such). In the same way, those who underestimate string theory, do not deserve to be called theoretical physicists. Because there are many ways in which string theory is true, going well beyond its original aims. (Those truths are many mathematical and subtle.)

The trust in academia is irrelevant to everything that we are discussing.

Since you have no valid arguments you use the ad hominem attack, pressuposing in me that I think of myself that 'I am superior and not biased'. But if I see a theorem and the theorem is proved then I must say that the theorem is true if I do not see any flaw. If I see a physical theory where concepts are introduced and used in a consistent way, where the ideas are genuine, simple and wonderful, and where one has tools to make constructive contributions in the quest and the hardships of having to explain experimental results then I speak of a good theory or a good proposal.

I summarize my position saying that dishonesty is not to be tolerated in science. Any crackpot who makes an impact in the media as a new Einstein is not to be tolerated. The only credibility is availed by hard work, by its consistency and by the scrutiny of that part of the scientific community which is entitled to do it: those who know what is at play because have worked hard to gain understanding.

Best.

fiksacie,

regarding your comment on Quantum Mechanics, the situation in those times was somehow analogous to the situation that we have nowadays with dark matter/energy. Although many geniuses contributed to the theory, it was clearly insatisfactory as a theory until the work by Heisenberg, Dirac and, finally, von Neumann, who rigorously and satisfactorily established its mathematical basis in the form that we know and use it today.

I have always been under the impression that the extraordinary rareness of the mathematical object that is being described by M-theory is (supposedly) part of what adds to its likelihood of being a true theory of quantum gravity. But if mathematics contains an infinite number of various objects, is not M-theory but one of an infinite number of possible candidates for quantum gravity, the other ones simply hitherto undiscovered?

Hermannus Contractus,

As for my "dishonesty", I should make it clear that I don't think "most string theorists are doing string theory because this is what Witten does". For one thing, it has been about 20 years since a significant number of string theorists have been doing "what Witten does". These days, few if any work on supermoduli and I don't think that will change.

I have written about Witten's influential role back in 1984, and I'll stand by what I've written on that. Scientists make judgements about what to do based on all the information at their disposal about a topic, and the views of someone whose opinion you value highly and trust are a significant piece of information. Witten's track record has certainly made him someone whose views should be taken very seriously.

Witten is on one end of the spectrum, on the opposite end there are people who write into blogs anonymously comparing skepticism that string theory is the only true way forward with Holocaust denialism.

Hermannus,

I have said several times that mathematical consistency is necessary, nobody is debating this. I am just saying the obvious, that mathematical consistency is not sufficient for a theory to be a description of nature.

I have no clue what you mean with 'string theory is true'. To me the only real truth is mathematical proof. I would agree that there are many mathematical truths that have been proved in string theory. But what does this have to do with the theory's potential to describe nature?

"With 'fringe science' I did not mean that there is few people working in it, but that the approaches are scientifically mediocre as to be considered valid proposals. "Again what do you mean with "scientifically mediocre". Do you mean you don't find the math interesting enough? Not beautiful enough? Not elegant enough? And what does this have to do with the question whether they describe nature correctly? Are you even interested in science? You do not once even address the question why you think that string theory is a good description of nature.

You talk about the 'beauty' and 'wonder' or some theory without taking into account that your perception of these matters isn't objective, you explicitly demonstrate that you are biased in your judgement of the viability of theories to describe nature. This isn't an attack on you, it's an observation.

Best,

B.

@ Peter Woit

If Witten has been influential and it is so highly regarded and esteemed, it is because of the great intrinsic quality of his work. Regrettably, you entertain ideas on how a theory is received, instead of its intrinsic value. In this way you contribute to create confusion among those who have not yet had the opportunity of approaching science seriously. And you make this seemingly out of personal animosity toward string theorists.

Therefore, I know the tricks of your rhetoric movements and it is not surprising for me that you add:

"Witten is on one end of the spectrum, on the opposite end there are people who write into blogs anonymously comparing skepticism that string theory is the only true way forward with Holocaust denialism."

If I write anonymously it is not out of cowardice. It is simply because I think that my name is totally irrelevant for what I am trying to convey, and to better emphasize the fact that the important thing is science, and not name dropping and recourse to authority. One should read the scientific literature making the effort to understand what is there. If one does this, then one immediately sees a very big difference between string theory and any other purported 'proposal'.

That with the Holocaust denialism, as I have said, was not a fortunate comparison and I must regret it (although I think that the point has been made clear).

@ Sabine

Let me clarify what I understand by "truth" and "scientifically mediocre" and in which precise sense I think that "string theory is true". Truth has many faces

- Excellent mathematical truth: a theorem is true if the logic of its proof is watertight.

- Excellent truth in experimental physics: the Franck-Hertz experiment is a most wonderful example of a dramatic truth revealed through an experiment of utmost elegance. An experimental design most cleverly thought out, in the most economic and clean manner to exactly prove what is under investigation.

- Excellent (and potentially revolutionary) truth in theoretical physics: You start from concepts that are well known, point its difficulties and its possible avenues to overcome them and then you introduce 'the ansatz', which leads to the astonishing and most desirable prediction that there should be a graviton there in order for the theory to make sense: the graviton is not built-in as premise, but derived as a consequence!

Furthermore: the ansatz has a beautiful, minimalistic, Occam's razor-like quality: it needs a minimum of assumptions, it overcomes known difficulties as the Coleman-Mandula theorem (through SUSY) in a most elegant and natural way.

String theory is true because it is dramatically beautiful. It is true as a poem is true. You can say that this is subjective. Well, if we discuss truth beyond mathematics, there might be certainly a subjective element. But subjective does not mean here, in any case, 'cheap' and debased to mere bourgeouis 'taste' or to the mere opinion of any postmodern fundamentalist crackpot. Subjective truth means here something deeply appealing to the human intellect of the individual that makes its own experience of such a truth.

Now let us look to a scientifically mediocre attempt: one is so distracted by so many technical pitfalls, inaccuracies and by the very ill-possedness of such a thing as, e.g. the Wheeler-De Witt equation, that one sees nothing else as a big heap of rubbish and folks fatally destined to devote attention to it. Such a proposal is like a 'poem' written by a poet that has no command of the word: It conveys no truth, one cannot feel any emotion and perceive any truth because the stumbling block of the technical defficiency is so evident and distracting.

Nature is economically beatiful. Its match cannot be a theoretical monstrosity or the botched job of mere crackpottery. Its theoretical partner must be (of necessity) beautiful and economic as well.

The best tradition in theoretical physics (variational principles) is consistent with this economy. String theory is heir to this tradition.

"Truth is beauty and beauty is truth. That is all ye need to know"

(Keats)

Dear Sabine,

Apologies if the comment below is painfully naive, for I am attempting to reason through the problem of “no-alternatives” like statistician rather than a physicist.

Say you have two models, P and G which work very well in their own domains applicability, but that have very little sensible to say about the others domain. A friend arrives saying there exists a model that unifies P and G with some additional structure and its called S. This is all very cool, because you thought those phenomena described by the simpler models were completely unrelated. So what to do now?

Well first remember, there is always an alternative: that the two well-functioning models P and G are distinct, however much that may grate on nerves.

Then one needs to determine the relative weight of evidence for the two hypotheses under consideration (S and P & G) given the experimental data D available. Following the rubric of decision theory, if S has a large amount of additional complexity with high uncertainty in each of the new parameters, it will have to match the data significantly better to be the chosen as the preferred hypothesis.

All this 'non-empirical' evidence amounts to is an attempt to justify (and quantify?) the prior belief in the truth of a particular model. That's all well and good, but for S to be the preferred model, i.e. p(S|D) > p(P&G|D), the prior odds ratio will have to be so heavily weighted towards S that I personally would find disconcerting.

This reasoning is inherently conservative, but I feel it does capture the reasoning behind the skepticism of some physicists.

Cheers

Hermannus,

I never said subjectivity is cheap... Scientists certainly work hard to obtain it ;) Before I comment on your elaborations about beauty, can you tell me whether or not you're a practicing physicist? Best,

B.

Of course I am a practicing physicist! And if I am expressing myself with certain 'violence' is because I thirst after strong arguments that may prove my ignorance (in order to learn ;) )

Hermannus,

Ok, thanks. I was afraid you'd say that. First let me note that Dawid wisely stayed away from the issue of beauty and elegance, though it was without doubt mentioned to him as a reason to believe in string theory. It's the most common argument that I get to hear.

As I said previously, I don't question whether string theory is beautiful or more beautiful than some other theory. I have my opinions, you have your opinions, and it's well known that the human sense of beauty is to some extent universal. Besides this, there is a selection bias here of course: if we thought math wass ugly we probably hadn't studied theoretical physics. My point isn't to which extent we agree or disagree on this.

What I am questioning is simply that relying on the human sense for beauty and elegance is a useful criterion to decide which theory describes nature. I cannot see any rationale for relying on this. For what I am concerned the math would be more beautiful if supersymmetry didn't have to be broken. Too bad that the universe doesn't comply. I'd also like Maxwell's equations better if there were magnetic monopoles. Again, the universe leaves my poor sense of beauty disappointed.

Think about this for a moment. You are trying to tell me that some fundamental theory that employs certain mathematical structures gives rise to conscious beings with a sense of beauty that prefers exactly these mathematical structures. And you expect me to buy this? That string theory tells me something about human consciousness?

400 years ago scientists believed a theory must reflect the will of god, which was a construct of their own mind. Now they believe it must be beautiful, which is also a construct of their mind and to me pretty much indistinguishable from trying to guess the will of god. I don't believe in your god. I was trained to trust in objectivity and avoid bringing my own biases into scientific assessments. It pains me considerably that so many theoretical physicists today aren't only blind to their biases but, far worse, openly insist on missionarizing others. Best,

B.

Well, I must confess you that my only god is Jesus Christ (together with the Father and the Holy Ghost, of course) and the only absolute truth that I recognize here on Earth is the cross.

I regard science more as a toy that the goodness of God has given to human beings (His children) in order to be delightfully occupied celebrating His magnificence. We humans, tend to forget this, and tend to think that we know something.

As for string theory: it is economical, and economy in science reminds me of the lovely economy of our Lord Jesus Christ on earth. This economy reflects the wisdom of God and ot the Nature that he has created.

But I am only just another sinner

and now, I feel I have indulged too much in polemicks.

May God the Father, his Son our Lord Jesus Christ, the Holy Ghost and the splendid amiableness of our Lady the Virgin Mary be with you and advance you to glory through the ways of peace and love. I must now go back to my science. Best.

lubos wrote "Why is it relevant? Every time one finds a relationship - let me talk about a string duality,"

Hi Lubos, String theorists use over complete functions which they fit to make a 'duality'. You've claimed on your blog that using over-complete functions....and fitting results in a duality with fundamental distinctiveness. Will you repeat that claim here?

Hermannus,

I realize this slightly off-topic, but what exactly do you mean by economical? Greatly increasing the model complexity without any noticable improvement in data fitting would hardly count, correct?

Sabine,

I enjoy reading your blog. But I wonder what you did to offend Lubos Motl:

"I am just so incredibly tired of all those low quality people who try to 'reduce' all these important physics questions to sociological memes and ad hominem attacks. You just can't that, you shouldn't do that, and it's always the people who 'reduce' the discourse in this lame sociological direction who suck."

"Sabine Hossenfelder is one of the people who badly suck."

He is one angry Czech!

Sincerely,

Bill Lama, PhD

Hermanicas contracticus or whatever his name is, talks the talk about beauty but it's pretty clear the ugliness just beneath the surface, his disrespect for other scientists who seek the truth by their instincts different to his, his ineffectual but notably vulgar analogies. For Science, really. And in the end, for Truth.

Unknown,

Regarding your question about priors. The thing is that in the present situation the probability that P&D agrees with all data is zero. As I elaborated on in my video, there is no data that can fit an inconsistent theory, so it is irrelevant exactly what the measurement would bring. Your assessment would be right were you only interested in the regime in which we have measurements, but in this case string theory qua assumption reproduces P&D, so all it says is that whatever the fundamental theory is, it must reproduce in suitable limits the theories for which we have experimental support. Best,

B.

Ok. Regarding asymptotic safety, I must say that I find it a valid scientific proposal. It is not an alternative to string theory, however, as claimed: I do not consider asymptotic safety and string theory to be mutually exclusive.

String theory is true and cannot fail to be true in some factual form. To speak about alternatives is, however, not just merely obnoxious but simply misleading. If one accepts that general relativity and quantum mechanics are well established theories, both mathematically and experimentally (and all physicists worthy of their profession accept that) one must also necessarily accept that string theory is their logical consequence.

There are no alternatives to string theory.

Indeed, I find asymptotic safety quite interesting. Thanks for your remark.

This is great!

Lectures on renormalization and asymptotic safety

Sandor Nagy

http://arxiv.org/abs/1211.4151

"But I wonder what you did to offend Lubos Motl:"Based on his blog, just being rational is probably sufficient. Whatever his accomplishments in mathematical physics, he is an AGW denier. Interestingly, his argument in this case is that the majority of the climate-science community are motivated by sociology and not science. :-|

Think about this for a moment. You are trying to tell me that some fundamental theory that employs certain mathematical structures gives rise to conscious beings with a sense of beauty that prefers exactly these mathematical structures. And you expect me to buy this?I am imagining an alien race that finds most mathematical structures ugly and in fact uses the pervasive ugliness of a theory as an argument for the validity of the theory.

Aforementioned

String theory is true because it is dramatically beautiful. It is true as a poem is true.Here is an excerpt of a true poem, true as string theory:

"It's a Snark!" was the sound that first came to their ears,

And seemed almost too good to be true.

Then followed a torrent of laughter and cheers:

Then the ominous words "It's a Boo--"

Then, silence. Some fancied they heard in the air

A weary and wandering sigh

That sounded like "--jum!" but the others declare

It was only a breeze that went by.

They hunted till darkness came on, but they found

Not a button, or feather, or mark,

By which they could tell that they stood on the ground

Where the Baker had met with the Snark.

In the midst of the word he was trying to say

In the midst of his laughter and glee,

He had softly and suddenly vanished away--

For the Snark was a Boojum, you see.

-------

String theory is a Snark that was a Boojum.

String theory is not a Snark that was a Boojum. And the Calabi-Yau manifolds are snarks that are quite alive and kicking.

String theory, being mathematically consistent, deep, beautiful and stemming directly from quantum mechanics and general relativity, belongs to the platonic world of mathematics as well. This means that, at least in that world, it cannot fail to be true. Beauty, says Plato, is that which partakes of absolute beauty. And the platonic world of mathematics can be put on equal foot as this world, since we do not understand this world and we do not want a 'cheap' understanding of this world, which debases everything deep that exists to the sophistry of mere opinion, reception and credentials (when not to ill defined concepts, too inadequate for what they claim to address).

There is a neurotic, restless and destructive way of looking at things that strives for consensus under the word called 'progress' and wants to violently move and dinamize things even when things require time (and this time can last 40, 50, 1000 years). As a consequence, 'truth', 'ethics' and 'honesty' seem to many to be mere options in the market that one can choose to follow or not because they seem to be claimed to be relative or 'subjective'. One can then also hid oneself in conformism and 'tolerance' of the state of affairs. In this very sense, it is safe today to publish a book such as "Not even wrong" counting beforehand with the smile of those individuals who experience doubt -something human, beautiful, scientific and legitimate- but are anxious to attach to an opinion of a so-called expert (something that is a product of our age). Such book would have never been written when string theory was born, at the time where it was 'modern' and 'exciting' and such public did not exist. Because that book does not offer a competent assessment of the science that is mentioned there.

Hermannus,

Appealing to beauty isn't science. As to the rest of your comment: Empty words of somebody who has run out of arguments. Besides this, I will not approve of any more comments of yours that insult Peter because it's not conductive to a reasoned exchange.

I am not insulting Peter Woit (whom I do not personally happen to know) but opposing resistance to the product that is published and available to everyone. Fortunately, a person has more depth than just any work (even when "for their fruits ye shall know them"). But if one expresses oneself in a bland manner, I doubt whether this will lead someone to reflect.

This is why I do not sign with my own name: I do not want to attack ad hominem anyone and signing with my own name is to move the aggresivity forward to the extent of having a particular personal animosity with some individuals (or collectives). I would like to reflect on the fruits, not on specific people.

Appealing to beauty is science because otherwise nothing that occupies us would exist (human beings neither).

But it is clear to me that my words are empty to you and I shall not disturb you anymore.

Well I think that all went very well. Big hug anyone?

Ah, in the Platonic world of Mathematics, yes or not to the Axiom of Choice?

On the reasonable ineffectiveness of mathematics:

1. A comment on Peter Woit's blog.

2. D. Abbott in an IEEE paper (PDF)

"Mathematics is a product of the imagination that sometimes works on simplified models of reality."

From the D. Abbott paper, "John von Neumann stated all this more succinctly: ‘‘The sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct is solely and precisely that it is expected to work’’

Arun,

Thanks for the reference to the Abbott paper, this is very interesting!

Arun said: 'From the D. Abbott paper, "John von Neumann stated all this more succinctly: ‘‘The sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct is solely and precisely that it is expected to work’’'

Sure, but unless you believe von Neumann also believed science-as-mathematical-models was a field yielding theories absent of any explanatory implications, and indeed that he was hostile to the very intents of resolving theory into explanatory forms, then your position does not support the position for which you apparently nominate it.

We can do better than isolated statements from the great and good of scientific history. We can peruse scientific history itself. Are you suggesting that the scientific revolution has not transfored our explanations of the world? Don't let me put words in your mouth though. Please clarify what your position actually is.

Just a few final remarks before I completely disappear from this site.

Beauty is truth as proved by Einstein's words regarding Franck-Hertz experiment: "It is so lovely: It makes you cry".

Lovely = Beautiful

General relativity is lovely, quantum mechanics is lovely, string theory is lovely, supersymmetry breaking is lovely.

Very, very soon, superpartners will be found: the sgluino and the s-hermannus-contractino and a host of new particles in that direction. Perhaps we shall see this happening already in the second run. Then, the whole scientific community will cry of joy, we shall see Gross (and also Klein) celebrating "the power and the glory of string theory" and all your business shall come to an end.

I hope to see this happening very very soon!

Best regards

Well, Chris Mannering, John Von Neumann's statement can be found in his essay "Method in the Physical Sciences". You can find part of it exposed in Google Books, in "The Neumann Compendium". A fuller quote is:

"To begin, we must emphasize a statement which I am sure you have heard before, but which must be repeated again and again. It is that the sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct is solely and precisely that it is expected to work - that is, correctly to describe phenomena from a reasonably wide area. Furthermore, it must satisfy certain esthetic criteria - that is, in relation to how much it describes, it must be rather simple. I thin it is worth while insisting on these vague terms - for instance, on the use of the word 'rather'. One cannot tell exactly how "simple" simple is. Some of the theories that we have adopted, some of the models with which we are very happy and of which we are very proud would probably not impress someone exposed to them for the first time as beinig particularly simple.

Simplicity is largely a matter of historical background, of previous conditioning, of antecedents, of customary procedures......"

John von Neumann has a version of "unexpected explanatory coherence" but it is of a somewhat different form than that described by Dawid, I think (going by Bee's essay).

Here goes (extended quote) from "Method in the Physical Sciences":

The ability to describe -- or to predict -- correctly is important in such a model, but it need not be decisive per se. Also, in scientific prediction it does not matter enormously whether prediction occurs before or after the fact. Of course, it must be correct. However, as I mentioned above, it is considered important that the material which has been correctly described or predicted should be heterogenous. Let me analyze this requirement in somewhat more detail.

If possible, the confirmation should not all stem from one area alone. In this sense, it is considered particularly significant to find confirmations in areas which were not in the mind of anyone who invented the theory. Thus, if you discover that the theory, which was necessitated by difficulties in one area, describes things correctly in entirely different areas, this is highly significant. It is even more important, if things have not been previously very harmonious in these latter areas and there was no sense of optimism about them.

In this regard, the enormous authority of quantum mechanics is typical. It was probably strongly conditioned by the fact that quantum mechanics came into being because of various difficulties in spectroscopy and of various other problems of atoms and molecules which are variously connected with spectroscoopy, but that it was then suddenly found capable of describing or predicting correctly various things in chemistry, in solid-state physics, and even to have some bearing on epistemology. These were hardly on anyone's mind at the beginning.

Lastly for my position - I have considerable sympathy for the D. Abbott position. Perhaps mathematics is an expression of sufficiently sophisticated neural networks. How to decide?

Sabine/Hermannus,

I'm finding it rather amusing for my book to be attacked as "conformist" and catering to the "consensus". Things really have changed in the last 10 years, used to be it was attacked as the product of a loser in the marketplace of ideas...

Hi Aseun - What in your view is the relation these two further quotes and the first one? I think he's returning to the same position in a bit more detail. The first statement remains a full capture of his position, or do you say not?

So, I'm not sure what has been added by the two statements. I wasn't arguing that von Neumann was lying about what he really believed, or that he believed it only shallowly.

What I'm suggesting is that his statement has an implicit context within which it sits. Was von Neumann suggesting that Science has not advanced our explanations of the world?

Of course he wasn't, because that would be a ridiculous thing to say. He was talking about the necessary redundancy between, on the one hand the component of scientific knowledge that is mathematical, and on the other hand, the ways and forms in which we think, write, school-the-young.

Both are Science. They are two mutually redundant parts that make up the singular, pairing. A bit like those dualities you stringy people keeping knocking into!

So that's the fact of scientific history. It's there, physically, as the body of knowledge.

What I was asking you, was what personaly position of your own, do you believe his statement supports. And why?

There's obviously a few typo's in play there. I'm sorry about that. Aseun = Arun.

As an example of how beauty is in the eye of the beholder, I found the paper by Dr. Abbott (for which thanks to Arun) beautiful in its expression of a non-Platonist view of mathematics.

Of course this is partly because it dovetails with my own view that math is thinking/thinking is math, and that science, engineering design, and human thinking itself is based on the evolutionary algorithm of random generation, survival of the fittest, and memory (i.e., reproduction of ideas through time) - which elaborates itself with analogs of cross-breeding and so on as simple ideas are combined and become more complex. Probably a Platonist would not see the same beauty.

Similarly, an alien race probably would not find human physiognomy beautiful. Evolution produces subjective standards of beauty.

(1) I really think the advancement of science requires all sorts of approaches. It requires Platonists and non-Platonists, and other varieties. The nature of reality is not captured in any one approach or ideology. The initial solution to a problem may come by any method; as our understanding deepens we cast the solution to conform to various forms.

(2) Currently, I think there is a predominance of Platonists.

(3) Platonism can go to an extreme. The 17th century Jesuit resistance to infinitesimals (or D. Abbott's example of the controversy over negative numbers) derives from a Platonist position.

(4) Newton's law of gravity is not an explanation; and what it produces is a description, not an explanation. The descriptions of the manifold phenomena encompassed by Newton's laws are in terms of a few central ideas, and we mistake these for explanations. IMO, the big conceptual barrier to arriving at quantum mechanics was the mistaken idea that Newton's law was an explanation. Explanations are either right or wrong; descriptions are valid within a certain range of validity. When we say something is fundamental - as in fundamental law of physics, we are saying we think the range of validity of the description is the entire universe. But the fundamental nature of a physical law is provisional, and so what it provides is at best a provisional explanation.

I do not deny the value of making the hypothesis that some laws are fundamental, explanatory, and exploring the consequences of that hypothesis.

(5) Descriptions are what can be compared between model and scientific experiment. Explanations are not directly compared.

(6) So, string theory might even be the basis for a fundamental explanation of nature, but unfortunately, it doesn't describe anything that is accessible by scientific experiment.

@ Arun

> (2) Currently, I think there is a predominance of Platonists.

I do not think so. Currently, for example, there is a predominance of the image over the equation. The extreme case for example is Stephen Wolfram, who in "A new kind of science" suggests that simple programs make traditional mathematics obsolete and that the only way of understanding cellular automata is to run a computer and see what pattern arises. (Fortunately, that traditional mathematics cannot tackle cellular automata has recently been refuted: see the works by Israeli, Goldenfeld and Garcia-Morales.)

People usually hate mathematics and this attitude is not helped by most professionals who tend to introduce more and more pictures and videos in PowerPoint presentations and seem to disregard the blackboard.

If one hates or disregard abstraction, one is not a Platonist.

@JimV

>Similarly, an alien race probably would not find human physiognomy beautiful. >Evolution produces subjective standards of beauty.

Beauty has absolutely nothing to do with physiognomy nor with sensible qualities. Beauty is (and opens) a transcendental realm. An all-encompassing realm where everything which is factually the case in the universe enters. This is something that non-Platonists do not understand.

Beauty is something compelling to the intellect (and to the intellect alone). And the experience of beauty is a scientific experience, as the example of Einstein and the Franck-Hertz experiment above shows, because it compellingly and transcendentally connects the human intellect with the dance of the cosmos and eternity.

These postmodern sociologists, lovers of neutrality and impersonality, and more and more profesionals of science, contend that 'pathos' does not belong to science and only just mere rationality. They do not see that their confidence in science is at the end just 'faith' in science and that faith has always an "irrational" dimension. Wittgenstein says this very nicely: "I can only guess that tomorrow the sun shall shine again, but I cannot say that this is a de facto truth". If one completely abolishes pathos in science, one eliminates the dramatic dimension of the truth as well, and one is left with nothing: Just the business of the shadows.

@Peter Woit

In my humble opinion, in your book you promoted the problem with the cosmological constant (something recognized by the string theory community: Witten says for example that the value of the cosmological consant is the most puzzling and dramatic problem in his career) to the 'not-even-wrongness' of the whole string theory. From this move one can only expect angry reactions from those that have been working many years on the theory so as to be able to appreciate and discover a lot of beauty in it: this beauty wants to be disclosed to the general public, but due to the complexity of the theory this cannot happen immediately. By introducing such a move from your part, you introduced a lot of violence, since you introduced external factors, alien to the theory, that accelerated a negative general view on string theory (before many just can understand and appreciate what string theory is at all), undermining also the confidence of 'weaker souls' who were working in string theory on what they were doing.

At the risk of prolonging a not-very meaningful discussion:

The fact that not all here or elsewhere can agree on the meaning of beauty or what is or is not beautiful seems quite consistent with the concept that beauty is subjective rather than some objective Platonist ideal.

I have some sympathy with the notion that the mathematics we evolve could be considered part of a conceptual Hilbert space of algorithms and conclusions that follow from certain premises (theorems). However I consider that space large enough that our journey in it is rather random, and like biological evolution, could have produced wildly different results from the same starting point. (Dr. Abbott gives some examples of this.)

If beauty is to be considered a function of intellect alone, then flowers and children and kittens and painted turtles (Chrysemys picta) either are not beautiful, or are only appreciated to the fullest by geniuses. I cannot agree with this, but suspect it is a matter of semantics.

@Hermanus:

"Very..... soon superpartners will be found..."

It must be great to have supernatural capabilities.

Repent, prophets are among us!

"..there is probably less difference between the positions of a mathematician and of a physicist than is generally supposed, [...] the mathematician is in much more direct contact with reality. This may seem a paradox, since it is the physicist who deals with the subject-matter usually described as ‘real’, but [...] [a physicist] is trying to correlate the incoherent body of crude fact confronting him with some definite and orderly scheme of abstract relations, the kind of scheme he can borrow only from mathematics."

G. H. Hardy

"The mathematician’s patterns, like the painter’s or the poet’s must be beautiful; the ideas like the colours or the words, must fit together in a harmonious way. Beauty is the first test: there is no permanent place in the world for ugly mathematics."

G. H. Hardy

"… there is no scorn more profound, or on the whole more justifiable, than that of the men who make for the men who explain. Exposition, criticism, appreciation, is work for second-rate minds."

G. H. Hardy

"There is no place in the world for ugly science"

Hermannus Contractus

JimV said "The fact that not all here or elsewhere can agree on the meaning of beauty or what is or is not beautiful seems quite consistent with the concept that beauty is subjective..."

Opinion: beauty is objective, but beauty also exists on many levels, and it is for the beholder to say what level the beauty of a thing most comes across

"...rather than some objective Platonist ideal."

There's been some talk of whether Platonists are growing in number and are the dominant or is the other camp. But is there another camp? I think it's only Platonists - self-styled - that find that playground particularly interesting. How often does one find a fiercely passionate Aristotelian with several mates ready to jump in, going around issuing decrees who gets to be a Platonist and relegation sermons to the unfortunate inadequate.

It's a bit like going back to 1900's America and asking whether cowboys or Indians are dominant.

Hermannus, I think what you've been showing a fair amount of arrogance here in your judgment of string theory and to those who disagree with it. Beauty is not some immutable thing. It changes with increasing knowledge of the world. Peter Paul Rubens painted idea of beauty in women was characterized by, what many would say, women that carried some extra weight. These highly voluptuous portrayals of women was probably not exceptional in the 1600s when he painted. That period was coming off an era when scarcity, famine and plague were fairly common and very thin women were the norm and signified a state of unhealthiness. No wonder big women were thought to be beautiful.

The world has changed and in most parts of the world it is now far easier to be fat than thin. "Thin" is now rare and considered beautiful and exotic. So the changing world directly forms our view of beauty, even if we don't recognize it.

Your own views on the bible teachings show that you do not keep up with the changing times and our new knowledge and experience of the world. Is it a stretch to say that a temperament like yours extends to your view of string theory? I don't think so. I would say that your sense of beauty is crippled by your lack of acknowledgment of the current sense and knowledge of the world.

Lest you think I'm saying that you're not very bright, well, I actually may be saying just the opposite. (I don't know you.) A recent book I read, "The Righteous Mind", by Jonathan Haidt explained a lot about what was troubling me in physics: namely that very intelligent people seem to get "stuck" and are very defensive about changing their positions. A short summary, which was really just an aside in the book, was that intelligent people often are very used to being right in their early years and being always at the head of their class. It breeds a kind of arrogance. Later in life, many of these high IQ people develop theories of their own. But because they are used to thinking they are right and others are wrong from their own early experiences, they use their high IQs to instead defend their ideas and they are very good about doing that, and can be very pugnacious even in the face of lots of opposing facts. In effect they are using their brain power to ignore new information about the world and instead use it to protect their egos which have become quite big from their early experiences and feedback from authority figures that they are superior.

The interesting thing about all this we who are less intelligent (at least in the facile IQ way) never have become so adept at defending our positions and don't have as much confidence to bulldoze our way when opposing facts of the world disagree with out theories. Instead we reexamine what we know and are open to new ideas that may be much more sensible. Do you think it is a freaky accident that people like Roger Penrose and Richard Feynman both have only mediocre IQs of 125? It might actually be statistically significant in their openness to non-authoritarian ideas.

I can identify with them because my mind is at that same mediocre level as measured by IQ tests.

Oh, and by the way, string theory has nothing whatever to do with asymptotically safe gravity and everything to do with Twistor Theory and the CFT constructed within that framework.

Sci3nce was beautiful when the earth was flat and feathers fell slower than lead. Beautiful and simple.

And useless.

As useless as M^500 theories :) or superpartners just 1TeV away.

I agree. Michelangelo's David is beautiful.

And completely usel3ss.

@Eric

Thank you very much for your reasoned and helpful comment. I totally agree with much with what you say. I am sorry if you think that I have been showing a fair amount of arrogance "in my judgment of string theory and to those who disagree with it".

Although I accept your criticism I want to note the following. I do not think that string theory is the ultimate theory and the ultimate truth. I have also recently published my own approach to relativistic quantum mechanics in a peer reviewed journal, and this approach has absolutely nothing to do with string theory (perhaps).

My approach would probably fiercely attacked by string theoreticians (I don't know).

If I have rather passionately defended string theory is because I cannot accept that something which is of so much value is rejected out of hand (a situation that many people dream about even when they make their business also thanks to string theory: i.e. negating its value).

I do not agree with what you say about Rubens. In order to survive, he probably had to sell his paintings to someone who just only look at the women there (and who thought that the women that are beautiful were the fat ones for the reasons you argue). But I think, for an artist, a fat woman is in principle as beautiful as a thin one: What makes a painting beautiful is not just depicting someone regarded as beautiful. What makes something beautiful is how everything is in coherence and harmony. You can paint very ugly things and still achieve something beautiful if you are a master and can properly integrate them in harmony (coherence). I would say, the uglier the things that you satisfactorily integrate, the higher the value of the work of art.

I totally agree with your paragraph

"Your own views on the bible teachings show that you do not keep up with the changing times and our new knowledge and experience of the world. Is it a stretch to say that a temperament like yours extends to your view of string theory? I don't think so. I would say that your sense of beauty is crippled by your lack of acknowledgment of the current sense and knowledge of the world"

and I have nothing to add here. You are true.

Regarding the IQ, I think that such coefficient measures nothing and only introduces violence. A person who is widely regarded as intelligent can behave as a complete fool and be an asshole, and a person who is regarded as a complete fool may also display baffling and decisive sparks of intelligence (and what is most important: an immense heart). I think, from your clever comment, that you also do not fail to notice this.

And I think that we have nothing and that everything is given (or subtracted) to us. Yes, I believe in an absolute and immobile beauty.

If we are not humble, then we shall have the opportunity of tasting the bitterness of it. I was not humble in my past and I have learnt the joy of what humbleness means: everything serves you in the right place.

I must not go on and try to fight my temptations of intervening here. It is clear to me that all you are not at all interested in what I say because of the (truthful) reasons that you mention in your paragraphs.

People feel alone in this world or this galaxy because they have a flawed notion of distance. If one loves, everything is near. The whole stringy universe in heart and mind.

Best regards.

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